Implementation of the /db/_bulk_docs endpoint. Innitial commit.
Fix normalizer and normalizer tests.
Tests fixes.
Check if is bulk doc or single doc.
Add update entities test case.
Make sure that the entity is deserialized to the correct state so that saving doesnt break.
Continued the implementation of the ContentEntityNormalizer with proper UUID mappings
Converted to Unix line breaks after Eclipse messed it up
Add more test cases, remove commented code.
Change the url to follow the specifications.
Remove is_array() check.
Add new line at the end of the file.
Wrap the bulk doc entities in te 'docs' key.
Issue #2282285 by jeqq, dixon_: Implement the /db/_bulk_docs endpoint.

Merge branch '2282285-_bulk_docs-endpoint' into 8.x-1.x